CALDUR® PM value – Titrimetric
PM value determination (p-value/m-value) in water by acid-base titration (0.5 / 0.25 mmol/l per drop)
Private customers can also find our range in our partner store Ampha-Analyse.
Reagent for CALDUR® PM value – Titrimetric:
See also:
CALDUR® PM value test set – Titrimetric
What is the PM value measured for?
The PM value (p-value and m-value) describes the acid and base capacity of water and is a central parameter in boiler water and cooling water monitoring.
The p-value (phenolphthalein value) indicates the base capacity up to pH 8.2 and shows the concentration of hydroxide and carbonate ions. It is particularly important for monitoring alkalinity in boiler water and cooling water systems.
The m-value (methyl orange value) indicates the total alkalinity up to pH 4.3 and also includes the hydrogen carbonate ions. It is a measure of the total acid capacity of the water.
Regular monitoring of the PM value is essential for the safe operation of steam boiler systems, cooling water systems and water treatment systems. Incorrect alkalinity values can lead to corrosion, boiler scale or foaming.
How does the test set work?
The CALDUR® PM value test set works according to the proven acid-base titration method. The water sample is first mixed with a pre-reagent and an m-reagent (indicator). The titration solution is then added drop by drop until a clear color change indicates the end point.
Measuring principle: Each drop of titration solution corresponds to 0.5 mmol/l (for standard sample volume) or 0.25 mmol/l (for double sample volume). The number of drops multiplied by the drop value results directly in the PM value.
Calculation: Number of drops × 0.5 (0.25) mmol/l = PM value.
Advantages of the CALDUR® test set
- p-value and m-value in one test set
Comprehensive alkalinity determination with one test kit
- Measured value 0.5 (0.25) mmol/l per drop
Precise measurement for system monitoring
- 100 determinations per set
Economical for regular operational control
- 3 reagents for maximum accuracy
m reagent, pre-reagent and titration solution
- Proven acid-base titration
Reliable and reproducible results
Areas of application
Carrying out the measurement:
Determination of the p-value:
- Fill the water sample into the test tube up to the mark
- Add pre-reagent and mix
- Add titration solution drop by drop until the first color change occurs
- Count drops = p-value in mmol/l (× drop value)
Determination of the m-value:
- Add m reagent to the same sample and mix
- Continue to add titration solution drop by drop until the second color change occurs
- Total number of drops (from start) = m-value in mmol/l (× drop value)
Tip for best results
For greater accuracy, use twice the sample volume – the drop value is then halved to 0.25 mmol/l. This enables a more precise determination, especially with low alkalinity values.
Important notes
- Add the reagents in the specified order
- Slowly add titration solution drop by drop
- Mix thoroughly after each drop
- For heavily stained samples: filter or dilute the sample
Measuring range
| Property | Value |
|---|---|
| Measured value per drop (standard volume) | 0.5 mmol/l |
| Measured value per drop (double volume) | 0.25 mmol/l |
| Measuring range | From 0.25 mmol/l (by drop counting) |
Number of drops × 0.5 mmol/l = PM value (for standard volume).
For double sample volume: number of drops × 0.25 mmol/l.
Example: 10 drops × 0.5 = 5.0 mmol/l.
Number of possible determinations
With one CALDUR® test set PM value you can carry out approx. 100 measurements.
Measuring accuracy and reproducibility
Readability: ± 0.5 mmol/l (per drop at standard volume)
Reproducibility: Very good if the application instructions are followed
Interference: Strongly colored or true samples can make the color change more difficult. In this case, filter or dilute the sample.
Specifications at a glance
| Property | Value |
|---|---|
| Parameters | PM value (p-value / m-value) |
| Item number | 31-071590 |
| Method | Titrimetric (acid-base titration) |
| Measuring principle | Drop counting up to the color change |
| Measured value per drop | 0.5 (0.25) mmol/l |
| Analysis time | 2 minutes |
| Number of determinations | approx. 100 |
| Reagents | 3 (m-reagent, pre-reagent, titration solution) |
| Packaging | Hinged lid box |
| Packaging size | 103 x 91 x 36 mm |
Scope of delivery
| m-Reagent (indicator) | Dropper bottle (shelf life 24M) |
| Pre-reagent | Dropper bottle (shelf life 24M) |
| Titration solution | Dropper bottle (shelf life 24M) |
| Test tubes | With markings |
| Operating instructions | DE/EN |
Additional information
| Packaging | Hinged lid box, Refill pack |
|---|---|
| Product category | Test kit |
Flyer
Operating instructions
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